%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2010-2013. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%%
%% %CopyrightEnd%
%%
%%
%% Statistics collector.
%%
-module(diameter_stats).
-behaviour(gen_server).
-export([reg/2, reg/1,
incr/3, incr/1,
read/1,
flush/1]).
%% supervisor callback
-export([start_link/0]).
%% gen_server callbacks
-export([init/1,
terminate/2,
handle_call/3,
handle_cast/2,
handle_info/2,
code_change/3]).
%% debug
-export([state/0,
uptime/0]).
-include("diameter_internal.hrl").
%% ets table containing 2-tuple stats. reg(Pid, Ref) inserts a {Pid,
%% Ref}, incr(Counter, X, N) updates the counter keyed at {Counter,
%% X}, and Pid death causes counters keyed on {Counter, Pid} to be
%% deleted and added to those keyed on {Counter, Ref}.
-define(TABLE, ?MODULE).
%% Name of registered server.
-define(SERVER, ?MODULE).
%% Server state.
-record(state, {id = now()}).
-type counter() :: any().
-type ref() :: any().
%% ---------------------------------------------------------------------------
%% # reg(Pid, Ref)
%%
%% Register a process as a contributor of statistics associated with a
%% specified term. Statistics can be contributed by specifying either
%% Pid or Ref as the second argument to incr/3. Statistics contributed
%% by Pid are folded into the corresponding entry for Ref when the
%% process dies.
%% ---------------------------------------------------------------------------
-spec reg(pid(), ref())
-> boolean().
reg(Pid, Ref)
when is_pid(Pid) ->
call({reg, Pid, Ref}).
-spec reg(ref())
-> true.
reg(Ref) ->
reg(self(), Ref).
%% ---------------------------------------------------------------------------
%% # incr(Counter, Ref, N)
%%
%% Increment a counter for the specified contributor.
%%
%% Ref will typically be an argument passed to reg/2 but there's
%% nothing that requires this. Only registered pids can contribute
%% counters however, otherwise incr/3 is a no-op.
%% ---------------------------------------------------------------------------
-spec incr(counter(), ref(), integer())
-> integer() | false.
incr(Ctr, Ref, N)
when is_integer(N) ->
update_counter({Ctr, Ref}, N).
incr(Ctr) ->
incr(Ctr, self(), 1).
%% ---------------------------------------------------------------------------
%% # read(Refs)
%%
%% Retrieve counters for the specified contributors.
%% ---------------------------------------------------------------------------
-spec read([ref()])
-> [{ref(), [{counter(), integer()}]}].
read(Refs) ->
read(Refs, false).
read(Refs, B) ->
MatchSpec = [{{{'_', '$1'}, '_'},
[?ORCOND([{'=:=', '$1', {const, R}}
|| R <- Refs])],
['$_']}],
L = ets:select(?TABLE, MatchSpec),
B andalso delete(L),
lists:foldl(fun({{C,R}, N}, D) -> orddict:append(R, {C,N}, D) end,
orddict:new(),
L).
%% ---------------------------------------------------------------------------
%% # flush(Refs)
%%
%% Retrieve and delete statistics for the specified contributors.
%% ---------------------------------------------------------------------------
-spec flush([ref()])
-> [{ref(), {counter(), integer()}}].
flush(Refs) ->
try
call({flush, Refs})
catch
exit: _ ->
[]
end.
%% ===========================================================================
start_link() ->
ServerName = {local, ?SERVER},
Module = ?MODULE,
Args = [],
Options = [{spawn_opt, diameter_lib:spawn_opts(server, [])}],
gen_server:start_link(ServerName, Module, Args, Options).
state() ->
call(state).
uptime() ->
call(uptime).
%% ----------------------------------------------------------
%% # init/1
%% ----------------------------------------------------------
init([]) ->
ets:new(?TABLE, [named_table, ordered_set, public]),
{ok, #state{}}.
%% ----------------------------------------------------------
%% # handle_call/3
%% ----------------------------------------------------------
handle_call(state, _, State) ->
{reply, State, State};
handle_call(uptime, _, #state{id = Time} = State) ->
{reply, diameter_lib:now_diff(Time), State};
handle_call({incr, T}, _, State) ->
{reply, update_counter(T), State};
handle_call({reg, Pid, Ref}, _From, State) ->
B = ets:insert_new(?TABLE, {Pid, Ref}),
B andalso erlang:monitor(process, Pid),
{reply, B, State};
handle_call({flush, Refs}, _From, State) ->
{reply, read(Refs, true), State};
handle_call(Req, From, State) ->
?UNEXPECTED([Req, From]),
{reply, nok, State}.
%% ----------------------------------------------------------
%% # handle_cast/2
%% ----------------------------------------------------------
handle_cast(Msg, State) ->
?UNEXPECTED([Msg]),
{noreply, State}.
%% ----------------------------------------------------------
%% # handle_info/2
%% ----------------------------------------------------------
handle_info({'DOWN', _MRef, process, Pid, _}, State) ->
down(Pid),
{noreply, State};
handle_info(Info, State) ->
?UNEXPECTED([Info]),
{noreply, State}.
%% ----------------------------------------------------------
%% # terminate/2
%% ----------------------------------------------------------
terminate(_Reason, _State) ->
ok.
%% ----------------------------------------------------------
%% # code_change/3
%% ----------------------------------------------------------
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
%% ===========================================================================
%% down/1
down(Pid) ->
down(lookup(Pid), ets:match_object(?TABLE, {{'_', Pid}, '_'})).
down([{_, Ref} = T], L) ->
fold(Ref, L),
delete([T|L]);
down([], L) -> %% flushed
delete(L).
%% Fold pid-based entries into ref-based ones.
fold(Ref, L) ->
lists:foreach(fun({{K, _}, V}) -> update_counter({{K, Ref}, V}) end, L).
%% update_counter/2
%%
%% From an arbitrary process. Call to the server process to insert a
%% new element if the counter doesn't exists so that two processes
%% don't insert simultaneously.
update_counter(Key, N) ->
try
ets:update_counter(?TABLE, Key, N)
catch
error: badarg ->
call({incr, {Key, N}})
end.
%% update_counter/1
%%
%% From the server process, when update_counter/2 failed due to a
%% non-existent entry.
update_counter({{_Ctr, Ref} = Key, N} = T) ->
try
ets:update_counter(?TABLE, Key, N)
catch
error: badarg ->
(not is_pid(Ref) orelse ets:member(?TABLE, Ref))
andalso begin insert(T), N end
end.
insert(T) ->
ets:insert(?TABLE, T).
lookup(Key) ->
ets:lookup(?TABLE, Key).
delete(Objs) ->
lists:foreach(fun({K,_}) -> ets:delete(?TABLE, K) end, Objs).
%% call/1
call(Request) ->
gen_server:call(?SERVER, Request, infinity).
